Per Share Data (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Dec. 29, 2017	Dec. 30, 2016
Schedule Of Earnings Per Share Basic And Diluted [Line Items]
Net income/(loss) attributable to Dolby Laboratories, Inc.	$ (81,622)	$ 53,374
Weighted average shares outstanding-basic (in shares)	102,552	101,483
Potential common shares from options to purchase common stock (in shares)	0	1,385
Potential common shares from restricted stock units (in shares)	0	1,008
Weighted average shares outstanding-diluted (in shares)	102,552	103,876
Net income per share attributable to Dolby Laboratories, Inc. - Basic (in usd per share)	$ (0.80)	$ 0.53
Net income per share attributable to Dolby Laboratories, Inc. - Diluted (in usd per share)	$ (0.80)	$ 0.51
Employee Stock Option [Member]
Schedule Of Earnings Per Share Basic And Diluted [Line Items]
Anti-dilutive securities, excluded from calculations (in shares)	2,424	739
Restricted Stock Units (RSUs) [Member]
Schedule Of Earnings Per Share Basic And Diluted [Line Items]
Anti-dilutive securities, excluded from calculations (in shares)	1,358	42